Mechanism of Organosol Formation from Copper Soap in Higher Alcohols

Abstract

A Cupper (II) Hexanoate (C6-Cu soap) was prepared by double-decomposition of sodium hexanoate and copper (II) chloride. A yellowish-brown organosol was formed by heating the copper soap suspended in 1-octanol, 1-decanol and 1-tetradecanol, respectively, at 100-170°C. The organosol particles obtained by heating the suspension in 1-decanol in concentraion of 10mg/5 ml at 170°C were found to be spherical by an electron microscope, whereas the particles obtained at 100°C in concentration of 500 mg/5 ml were cubic. The both spherical and cubic organosol particles were identified as copper(I) oxide by X-ray analysis. The influence of hydroquinone on the organosol formation was also examined.
The mass spectrum of the organosol showed many fine peaks around m/e=100-200, which were not found for copper soap itself, and a peak at m/e=99 of CH₃(CH₂)₄CO⁺. This result corresponds to the fact that an infrared absorption peak in 1590-1600 cm^-1 of COO- disappears and a new peak in 1710 cm^-1 of >C=-0 appears on heating.
These experimental results suggest that the C₈-Cu soap was reduced on heating in long-carbon chain alcohol to copper(I) oxide particles which are stabilized by oxidized product of the alcohol and hexanoyl derivative in the medium.